JP2010138382A - Improved hot melt composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot melt composition including an acid wax and an acrylate functional monomer free of acid groups. <P>SOLUTION: The hot melt composition includes an acid wax and an acrylate functional monomer free of acid groups. Upon application of actinic radiation, the hot melt composition is cured to form an etch resist. The hot melt composition may be used in the manufacture of printed circuit boards, optoelectronic and photovoltaic devices. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hot melt composition which is cured by exposure to actinic radiation, functions as a plating resist and an etching resist, and can be easily peeled off from a substrate. More particularly, the present invention cures upon exposure to actinic radiation, functions as a plating resist and etching resist, is easily peelable from the substrate, and has a high acid number wax together with an acid group-free acrylate monomer. The present invention relates to a hot melt composition comprising:

  A hot melt is a solid phase at ambient temperature, but exists in a liquid phase at high operating temperatures in an ink jet printing apparatus. At the ink jet operating temperature, liquid hot melt droplets are ejected from the printing device, and when the droplets contact the surface of the printing material, the droplets cure and form a predetermined pattern of droplets.

  Hot melts have been used in direct and transfer printing processes. The hot melt is typically cast into a solid stick and placed in an inkjet printing apparatus. The temperature of the inkjet device is raised to an operating temperature at which a liquid phase having selective fluid properties is formed. The hot melt is then held as a liquid at the operating temperature in the reservoir and print head of the inkjet printer. The liquid phase hot melt can then be applied in a predetermined pattern onto the substrate. While hot melts have been used for some time in the traditional printing industry, the electronics industry has the potential of such compounds to solve problems in the manufacture of electronic devices, such as printed circuit boards (PCBs). Has begun to evaluate various uses.

  PCBs are typically manufactured in a complex process such as using a dry film negative photoresist process with 6 or more stages. First, a dielectric material is laminated or coated with copper, and then a photoresist layer is overcoated on the copper surface. A phototool is prepared which is the negative of the necessary conductive circuit of the printed circuit. The phototool is placed directly on the photoresist layer to polymerize and cure the areas exposed to UV light to produce the necessary conductive circuit latent image in the photoresist layer. The photoresist layer is then developed to remove unexposed areas of the photoresist. If the photoresist layer contains free carboxyl groups, this chemical treatment is typically a mild alkali.

  The exposed copper is then selectively removed from areas not protected by the photoresist layer by chemical etching. Finally, the exposed areas of the photoresist layer are chemically removed using, for example, aqueous strong alkali, if the photo layer contains free carboxylic acid groups.

  Although this process is widely used in PCB manufacturing, the process is tedious and expensive because the photoresist layer is manufactured separately and applied over the entire area of the copper / dielectric stack. And there is a lot of waste of material. In addition, many phototools that contain a negative image of the desired conductive circuit so that diffraction of UV light occurs and results in development and polymerization in areas of the photoresist that are not directly below the UV transmission area of the phototool. In the case of a distance from the phototool layer. Such issues must be considered if the manufacture of the phototool can reduce the density and definition of the conductive circuit. Furthermore, the photoresist chemical structure must be carefully controlled because removal of the photoresist both before and after exposure to UV light is dependent on the alkaline processing agent. If the unexposed photoresist is incompletely removed, or if some of the exposed and polymerized photoresist is removed before chemical etching of the copper, the density and integrity of the intended conductive circuit is high. Can be exacerbated. Thus, because inkjet printing technology eliminates the need for photoimaging and development processes, there is great interest in applying photoresists and similar materials to specific areas of copper / dielectric laminates using inkjet printing technology. Existing.

  In the case of inkjet printing, the image or negative image is made digitally available directly from the computer, the number of process steps is halved, and the need for various removals of photoresist using various strength aqueous alkalis Is avoided. Also, there is a possibility of improved clarity and density of the circuit because there are no photo tools that are separated from the photoresist layer. Also, since photoresist is applied only to areas that are to be protected from chemical etching, there is also a cost reduction for the photoresist material.

  Substantially complete removal of photoresist or similar material is highly desirable for lithography art workers. If the photoresist residue remains on the substrate after removal, the residue may exacerbate further processing of the substrate. For example, the photoresist is deposited on the PCB and functions as a negative mask for forming a circuit pattern. The portion of the substrate that is not covered with the mask is etched away using an etchant, and then the photoresist is stripped. Subsequent steps typically involve a bonding step or one or more metal plating processes. Residues remaining on the PCB after stripping can worsen bonding or metal plating, resulting in defective electronic devices.

  In addition to substantially complete removal, rapid removal of the photoresist is also important for lithography technology workers. Since much of the manufacturing of electronic devices involves an assembly line type process, faster removal makes the entire manufacturing process more efficient. Thus, there is a need for a photoresist or similar material that can be quickly and completely removed from a substrate.

  U.S. Pat. No. 7,427,360 discloses a method of manufacturing an electronic device by an ink jet process using an etching resistant ink instead of a conventional photoresist image forming method. The ink is a) 5 to 95% by weight of one or more monofunctional monomers, 30 to 90 parts of an acrylate functional monomer containing one or more functional groups and not containing acid groups; b) one or more acid groups. Acrylate functional monomer containing 1-30 parts; c) polymer or prepolymer 0-20 parts; d) radical initiator 0-20 parts; e) colorant 0-5 parts; f) surfactant 0-5 parts. And the ink has a viscosity of 30 cPs (mPa · s) or less at 40 ° C. The ink is substantially free of solvent and can be polymerized by actinic or particle beam irradiation. The ink can be peeled from the substrate using a base.

US Pat. No. 7,427,360

  Although there are ink jettable compositions and methods that can be used in electronic device manufacturing in place of conventional photoresist imaging methods, there is still an improved ink jettable formulation and method for manufacturing electronic devices. There is a need for.

In one aspect, the composition comprises one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators.
In another aspect, the method comprises:
a) providing a composition comprising one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators;
b) selectively depositing the composition on the substrate;
c) applying actinic radiation to the composition to cure the composition;
d) etching a portion of the substrate not covered with the cured composition;
e) using a base to remove the cured composition from the substrate to form a patterned article;
In a further aspect, the method comprises:
a) providing a composition comprising one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators;
b) selectively depositing the composition on the substrate;
c) applying actinic radiation to the composition to cure the composition;
d) metal plating on a portion of the substrate not covered with the cured composition;
e) removing the cured composition with a base to form a patterned article;

  The composition does not include an acid group-containing acrylate functional monomer. Acid groups that allow the composition to be removed from the substrate using a base are included in the acid wax component, which allows for quicker and substantially complete removal of the composition from the substrate. To. The acid wax value of the wax component is at least 50 mg KOH / g. The composition is substantially free of solvent, and thus the composition excludes unwanted solvents that can be toxic to workers and the environment.

  Compositions that are hot melts can be applied to a substrate by conventional ink jet devices, by conventional screen printing methods, and by conventional spray devices that can have nano-to-macro deposition capabilities. The composition is used as a resist. The composition can be used as a plating resist or as an etching resist. The composition and method can be used in the manufacture of electronic device components such as PCBs, and lead frames, optoelectronic devices, photovoltaic devices, and metal finishing of components and precision tools. They have good image sharpness and low fluidity due to their phase change properties.

As used throughout this specification, unless the context indicates otherwise, the following abbreviations have the following meanings: ° C = degrees Celsius; g = grams; L = liters; mL = milliliters; cm = centimeters; = Micron; dm = decimeter; Å = angstrom = 10 ⁻⁴ micron; = Amp; mJ = millijoules; W = Watts = Amps × volts; wt% = weight percent; cp = centipoise; UV = ultraviolet; IR = infrared; psi = pounds / inch ² = 0.06805 atmospheres = 1.01325 × 10 ⁶ dynes / cm ² .

  The terms “printed wiring board” and “printed circuit board” are used interchangeably herein. “Actinic radiation” means electromagnetic radiation capable of causing a photochemical reaction. “Viscosity” = the ratio of shear stress to internal fluid friction, or fluid shear rate. “Acid number” = grams of potassium hydroxide required to neutralize 1 gm of free acid to determine the free acid present in the material. Unless otherwise indicated, all percentages are by weight and are based on dry weight or solvent free weight. All numerical ranges include boundary values and can be combined in any order except where it is logical that such numerical ranges are constrained to 100% in total.

The combination of the acid wax and the acid group-free acrylate functional monomer is a hot melt and can be used as a resist, such as an etching resist or a plating resist, and at the same time substantially all of the composition is removed from the substrate. Compositions are provided that can be peeled from a substrate using a base stripper to be removed. The composition is resistant to acid etchants such as hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, organic acids such as carboxylic acids and mixtures thereof, and industrial etchants such as secondary chloride Resistant to copper (CuCl ₂ ) and ferric chloride (FeCl ₃ ). The composition comprises a substrate using a base stripper, for example an organic amine such as an alkanolamine, an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide and mixtures thereof, and alkali carbonates and bicarbonates. Is easily peeled off. Conventional strengths of both etchants and strippers can be used.

  The composition also includes one or more radical initiators that allow the composition to be cured by application of actinic radiation. Conventional methods known in the art can be used as sources of actinic radiation such as, for example, IR, UV and visible range actinic radiation and X-rays and microwaves.

  The composition is free of organic solvent and water. This is free of additional solvent or water in the composition, but there is a trace amount of solvent or water as an impurity or as a by-product in the manufacture of the various components used to make the composition. It means to go. Typically the composition is 100% solids by weight. The composition is low flowable, so the composition forms printed dots with aspect ratios (height versus width) ranging from 0.05 to 0.25, or such as from 0.08 to 0.18. They also form images with good image definition.

  The viscosities of the compositions are such that they can be used in many conventional ink jet devices. Typically, the viscosity of the composition ranges from 5 to 80 cp at 40 ° C to 150 ° C. Viscosity can be measured in a conventional manner, but is typically measured using a Brookfield viscometer with a rotating spindle, eg, a # 18 spindle.

  The ink jet device can store information digitally in its memory about the selective resist design applied to the substrate. An example of a suitable computer program is a standard CAD (Computer Aided Design) program for generating tooling data. The operator can easily change the selective deposition of the composition in the ink jet device by changing a digitally stored program. In addition, registration problems can be easily addressed. Ink jet devices can be programmed to be aware of potentially improper placement between substrates, such as in the manufacture of multi-layer PCBs, for example. If the device senses misregistration between substrates, the program changes the inkjet application of the resist mask pattern to avoid or correct misregistration between adjacent substrates. The ability to redesign the pattern from substrate to substrate reduces the possibility of misregistration between substrates and eliminates the costly and inefficient task of preparing multiple defined photo tools. Thus, the efficiency of selective deposition of resist and image formability is improved over many conventional methods.

  There are two main categories of inkjet printing: “Drop-On-Demand” inkjet and “Continuous” inkjet. Using drop-on-demand ink jet technology, the resist composition is stored in a reservoir and delivered to the nozzles of the printer printhead. There are means for ejecting a single droplet of the composition out of the nozzle and onto the substrate. Typically this is a piezoelectric actuation of the diaphragm in the chamber, which “pumps” the droplets out of the nozzle or locally heats the fluid to increase the pressure in the chamber. This causes the droplets to be ejected.

  In “continuous” ink jet printing, a continuous stream of resist composition is delivered to the nozzles of the printer printhead. Prior to exiting through the nozzle, the flow of pressurized composition proceeds through a ceramic crystal that is energized. This current causes a piezoelectric vibration equal to the frequency of the AC (alternating current) current. This vibration in turn produces droplets of the composition from the united flow. The composition becomes a continuous series of droplets, which are equally spaced and of equal size. A voltage is applied between the charging electrode and the droplet when the droplet surrounds the jet at a location where the droplet separates from the liquid flow at the charge electrode. When a droplet separates from the flow, each droplet carries a charge proportional to the voltage applied at the time it separates. When the droplets are formed, each droplet can be charged to a predetermined level by changing the charging electrode voltage at the same rate. The droplet stream continues its flight and passes between two polarizing plates maintained at a constant potential, for example, ± 0.1 kV to ± 5 kV, or for example, ± 1 kV to ± 3 kV. In the presence of this electric field, the droplet is redirected towards one of the plates by an amount proportional to the charge carried. Uncharged droplets are not deflected but collected in the garter and recirculated to the ink nozzles. Charged and therefore deflected droplets impinge on a radiant energy sensitive material that moves perpendicular to the direction of droplet deflection. By changing the charge on the individual droplets, the desired pattern can be applied. The droplet size can range from 30 μm to 100 μm in diameter, or such as from 40 μm to 80 μm, or such as from 50 μm to 70 μm.

  The inkjet process is adaptable to computer control for high speed application of continuously variable data. Inkjet printing methods can be divided into three general categories: high pressure (more than 10 psi), low pressure (less than 10 psi) and vacuum technology. All are known in the art or described in the literature and can be used in the application of resist compositions to substrates.

In addition to ink jet application, the resist composition can be applied by using screen printing and by a spray device having nano-to-macro-deposition capabilities. Examples of the types of spray devices that may be used are Optomec available from ^{(R) M} 3 D ^{(registered trademark).}

  The resist composition can be produced by any suitable method known in the art. The waxes, acid group-free acrylate functional monomers, and radical initiators typically included in the composition are solid or semi-solid at room temperature. They can be brought together in any order. They can be heated to soften or liquefy them so that they can easily be mixed together or with any additional ingredients. The components can be combined in any order in existing mixing or homogenizing equipment. Temperatures above 25 ° C. and up to 150 ° C. are typically used to mix the components. After the ingredients are uniformly mixed, the mixture can be cooled to 25 ° C. or lower to form a solid composition.

Acid waxes and combinations of acid waxes that provide the desired etch or plating resistance, flow, sharpening and stripping capabilities can be included in the composition. The acid functionality of the composition is substantially limited to acid waxes. Typically high acid waxes and mixtures thereof are used. The term “high acid wax” means a wax that has a high acid content of 50 mg KOH / g or more and is acid functionalized by 50% or more. Typically, the high acid wax has an acid content of 100 mg KOH / g or more, more typically 120 mg KOH / g to 170 mg KOH / g. One or more acid waxes can be blended together to achieve the desired acid number. The acid wax component determines the acid value of the resist composition. Such waxes are typically acid-containing crystalline polymer waxes. The term “crystalline polymer wax” means a wax material that includes an ordered array of polymer chains within a polymer matrix that can be characterized by a crystalline melting point transition temperature (T _m ). This crystal melting temperature is the melting temperature of the crystalline domain of the polymer sample. This contrasts with the glass transition temperature (T _g ), which characterizes the temperature at which the polymer chains begin to flow for amorphous regions within the polymer. The acid wax is included in the composition in an amount of 0.5% to 40% by weight of the composition, or such as from 5% to 25% by weight of the composition.

The carboxylic acid-terminated polyethylene waxes that may be used in the composition, structure _CH 3 _- having _{(CH 2) n-2 -COOH} ( average chain length of 16 to 50, which is a mixture of chain lengths "n") Examples include, but are not limited to, carbon chains and mixtures of linear low molecular weight polyethylene of similar average chain length. Examples of such waxes, n is UNICID 40 ^{(registered trademark)} 550, and n is including but UNICID ^(TM) 700 is a 50 without limitation. Both are available from Baker Petrolite (USA). UNICID and ^(R) 550 is 80% of the carboxylic acid functional groups, including the remainder is a linear low molecular weight polyethylene of a similar chain length, having an acid number and 101 ° C. The melting point of the 72 mg KOH / g. Examples of other waxes are n = 16 hexadecanoic acid or palmitic acid, n = 17 heptadecanoic acid or margaric acid or datsuric acid, n = 18 octadecanoic acid or stearic acid, n = 20 eicosanoic acid Arachidonic acid, n = 22 docosanoic acid or behenic acid, n = 24 tetracosanoic acid or lignoceric acid, n = 26 hexacosanoic acid or serotic acid, n = 27 heptacosanoic acid or carboceric acid, n = 28 octacosanoic acid That is, montanic acid, n = 30 triacontanoic acid or melissic acid, n = 32 dotriacontanoic acid or raschelic acid, n = 33 tritriacontanoic acid or cellomelicinic acid or phyllic acid, n = 34 tetratriacontane It has a structure of CH ₃ — (CH ₂ ) _n —COOH, such as acid, ie, gedic acid, n = 35 pentatriacontanoic acid, ie, celloplastic acid.

Examples of other high acid waxes included in the composition include high acid waxes having linear aliphatic chains of 16 or more carbon atoms. Typically, linear saturated aliphatic waxes with terminal functionalized carboxylic acids are used. Such waxes have an acid number greater than 50 mg KOH / g. More typically, such high acid waxes are montan waxes, n- _{octacosanoic,} CH ₃ - is _(CH 2) 26 -COOH, functionalized 100% acid. Such wax, manufactured by Clariant GmbH (Germany), Licowax having an acid value of 127~160mgKOH / g ^(R) S, Licowax having an acid number of 115~135mgKOH / g ^(R) SW , 100~115mgKOH / g Licowax ^(R) having an acid value of UL, and 130~150mgKOH / g of Licowax having an acid value ^(R) X101 but are not limited to these. Other suitable high acid waxes, some acid end are esterified, partially esterified montan acid wax, Licowax ^(R) U having an acid value of e.g. 72~92mgKOH / g.

  The melting point of such an acid wax is 65 ° C to 150 ° C. The melting point is typically 80 ° C to 110 ° C.

The acrylate functional monomer does not contain an acid functional group and contains a reactive vinyl group such as CH ₂ ═C (R) CO—, where R is hydrogen, alkyl or cyano. When R is alkyl, it is typically C _1-6 alkyl. Acid functional monomers are not included in the composition. Other limitations on the monomer include its compatibility with each other, compatibility with the other components of the composition, the inability to form another layer in the final resist composition, having a predetermined viscosity and base treatment. To be removed. The acrylate functional monomer has a molecular weight of 30,000 or less, or such as 20,000 or less, or such as 1,000 to 5,000. Typically, the molecular weight of the acid group-free acrylate functional monomer does not exceed 2,000.

Specific examples of acid group-free acrylate functional monomers include those available under the trademarks Sartomer ^™ , Actilane ^™, and Photoomer ^™ , such as Sartomer ^™ 506 (isobornyl acrylate ^). ), Sartomer ^™ 306 (tripropylene glycol diacrylate), Actilane ^™ 430 (trimethylolpropane ethoxylate triacrylate), Actilane ^™ 251 (trifunctional acrylate oligomer), Actilane ^™ 411 (CTF acrylate), Photomer ^(TM) 4072 (trimethylol propane propoxylate triacrylate), Photomer ^(TM) 5429 (a polyester tetra A Rirato) and there is Photomer ^(TM) 4039 (phenolic ethoxylate monoacrylate). Sartomer ^(TM) , Actilane ^(TM) and Phototer ^(TM) are each available from Cray Valley Inc. Akros BV and Cognis Inc. Trademark. Other examples of monomers include lauryl acrylate, isodecyl acrylate, isooctyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, 1,6-hexanediol Diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, butanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene Glycol diacrylate, triethylene glycol diacrylate, pentaerythritol tetraacrylate, tripropylene glycol diacrylate, isobornyl acrylate, 2-noacrylate Bornyl, cyclohexyl acrylate, a phenoxyethyl acrylate and tetrahydrofurfuryl acrylate. Such acid functional group-free acrylate functional monomers are included in the composition in an amount of 50 wt% to 80 wt%, or for example in an amount of 60 wt% to 70 wt%.

  The radical initiator can be any initiator, including any synergist typically used in the trade to initiate the polymerization of acrylate functional monomers. The initiator and, if present, the synergist can be activated by actinic radiation. Actinic radiation sources include, but are not limited to, mercury lamps, xenon lamps, carbon arc lamps, tungsten filament lamps, light emitting diodes (LEDs), lasers, electron beams, and sunlight. UV radiation, for example UV radiation from medium pressure mercury lamps, is typically used. Typically the radical initiator is a photoinitiator activated with UV light.

Examples of radical initiators and synergists are anthraquinones, substituted anthraquinones such as alkyl substituted anthraquinones and halogen substituted anthraquinones such as 2-tertiarybutylanthraquinone, 1-chloroanthraquinone, p-chloroanthraquinone, 2-methylanthraquinone, 2 Ethyl anthraquinone, octamethylanthraquinone and 2-amylanthraquinone, optionally substituted polynuclear quinones, such as 1,4-naphthoquinone, 9,10-phenanthraquinone, 1,2-benzanthraquinone, 2,3-benz Anthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,4-dimethylanthraquinone, 2,3-dimethylanthraquinone, 2-phenylanthraquinone, 2,3-dipheni Anthraquinone, 3-chloro-2-methylanthraquinone, retenequinone, 7,8,9,10-tetrahydronaphthanthraquinone, 1,2,3,4-tetrahydrobenzoanthracene-7,2-dione, acetophenone series such as acetophenone, 2 , 2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone and 2-methyl-1- (4-methylthio) phenyl-2- Morpholine-propan-1-one; thioxanthone series such as 2-methylthioxanthone, 2-decylthioxanthone, 2-dodecylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethi Thioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and dibenzyl ketal; benzoin and benzoin alkyl ethers such as benzoin, benzyl benzoin methyl ether, benzoin isopropyl ether and benzoin isobutyl ether; Azo compounds such as azobisisovaleronitrile; benzophenones, such as benzophenone, methylbenzophenone, 4,4-dichlorobenzophenone, 4,4-bis-diethylaminobenzophenone, Michler's ketone, and xanthone and mixtures thereof There is. Examples of commercially available initiators and synergists include Speedcure ^(TM) ITX, EHA and 3040, Irgacure ^(TM) 184, 369, 907 and 1850, Daracure ^(TM) 1173. Speedcure ^(TM) , Irgacure ^(TM) and Daracure ^(TM) are registered trademarks of Lambson Plc and Ciba GmbH, respectively.

  The radical initiator is included in an amount sufficient to allow the composition to cure when exposed to actinic radiation. Typically, such radical initiators are included in amounts of 0.1% to 10% by weight of the composition, or such as from 1% to 5% by weight of the composition.

  In some cases, one or more colorants may be included in the resist composition. Such colorants include pigments and dyes such as fluorescent dyes. Coloring agents can be included in the composition in conventional amounts that provide the desired color contrast. Suitable pigments include, but are not limited to, titanium dioxide, Prussian blue, cadmium sulfide, iron oxide, red mercury sulfide, ultramarine and chromium pigments such as chromate, molybdate and mixed chromate, and Lead, zinc, barium, calcium sulfate, and mixtures and modifications thereof, which are commercially available as yellow-green to red pigments under the names chrome yellow, lemon yellow, middle orange chrome, scarlet chrome and red chrome. ing.

  Suitable dyes include, but are not limited to, azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, cyanide dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone And dyes, naphthoquinone dyes, penoline dyes, phthalocyanide dyes and leuco dyes. Examples of fluorescent dyes include xanthenes such as rhodamine and fluorescein, biman, coumarins such as ambelliferone, aromatic amines such as dansyl, squarate dyes, benzofurans, cyanines, merocyanines, rare earth chelates and carbosols.

  Additional additives that are optional include, but are not limited to, surfactants such as nonionic, cationic, anionic and amphoteric surfactants, slip modifiers, thixotropic agents, blowing agents Antifoaming agent, plasticizer, thickener, binder, antioxidant, photoinitiator stabilizer, brightener, fungicide, bactericidal agent, organic and inorganic filler particles, leveling agent, opacifier, charging Examples include inhibitors and metal adhesives. Such additives can be included in conventional amounts.

  The resist composition can be used as an etching resist or as a plating resist. In general, a resist composition is selectively deposited on a substrate, followed by curing the resist composition with actinic radiation. After curing, an uncovered portion of the substrate can be etched to a desired depth, or can be etched to remove a region of the substrate surface to expose the underlying layer, forming a pattern on the substrate Can do. Since the etchant does not remove the resist from the substrate during etching, the resist composition functions as an etching resist. The etching resist is then stripped from the substrate, leaving a patterned substrate for further processing by conventional methods known in the art. Alternatively, the uncovered area of the substrate can be plated with metal and a pattern can be formed on the substrate, so that the resist functions as a plating resist. The plating resist is then stripped from the substrate, leaving a substrate with a metal pattern for further processing by conventional methods known in the art. Peeling is performed with a base at a temperature of 0 ° C to 100 ° C, typically 40 ° C to 60 ° C.

  As a variation of the above, the substrate can be selectively coated with resist on both sides and exposed to actinic radiation. Etching and plating can then be performed simultaneously on both sides of the substrate.

Etching can be done by methods known in the art suitable for the material comprising the substrate. Typically, etching is performed using acids such as hydrofluoric acid, nitric acid, phosphoric acid, hydrochloric acid, organic acids such as carboxylic acids and mixtures thereof, or industrial etchants such as secondary chloride. Performed with copper (CuCl ₂ ) and ferric chloride (FeCl ₃ ). Such etchants are well known in the art and can be obtained from the literature.

  Etching is typically performed at a temperature of 20 ° C to 100 ° C, more typically 25 ° C to 60 ° C. Etching involves spraying or dipping a resist coated substrate with an etchant in a vertical or horizontal position. Typically, spraying occurs when the substrate is in a horizontal position. This allows for quick removal of the etchant. The rate of etching can be facilitated by stirring the etchant, for example, using sonic stirring or oscillating spraying. After the substrate has been treated with the etchant, the substrate is typically rinsed with water to remove traces of the etchant.

  One or more metal layers may be deposited in a pattern formed on the substrate. The metal can be deposited by electroless, electrolytic, immersion or light induced plating. Conventional electroless, electrolytic, and immersion baths and methods can be used to deposit metal or alloy layers. Many such baths are commercially available or are described in the literature. Metals include, but are not limited to, noble metals and non-noble metals, and alloys thereof. Examples of suitable noble metals are gold, silver, platinum, palladium and alloys thereof. Examples of non-noble metals are copper, nickel, cobalt, bismuth, zinc, indium, tin and alloys thereof.

  Substrates include, but are not limited to, PCBs, semiconductor wafers such as photovoltaic cells and solar cells, and components for optoelectronic devices. In general, in the manufacture of PCBs, a resist composition is selectively deposited on a copper clad plate and cured using actinic radiation. The portion of the copper clad plate not covered with the resist is removed by etching. The resist is stripped from the board, leaving a circuit pattern on the board. In another embodiment, the resist is selectively deposited on the plate, rendered conductive with the metal seed layer using conventional processes, and cured using actinic radiation. The portion of the plate not covered with resist is plated with a metal or alloy. The cured resist is then stripped from the plate, leaving a metal pattern on the plate.

In general, in the manufacture of photovoltaic or solar cells, resist is selectively deposited on the front antireflective layer of a doped semiconductor wafer. The antireflective layer can be silicon, silicon nitride Si ₃ N ₄ , silicon oxide SiO _x , or combinations thereof. Typically, the antireflective layer is Si ₃ N ₄ . The semiconductor can be single crystal or polycrystalline. The resist is then cured with actinic radiation and portions of the antireflective layer are etched away to expose the emitter layer of the doped semiconductor (n + or n ++ doped). The cured resist is then stripped and the portion of the emitter layer not covered by the antireflective layer is plated with a metal or alloy to form current track and bus bar patterns.

  In another aspect, the resist may be selectively deposited on the backside of a doped semiconductor wafer that is covered with a metal, such as aluminum, copper, nickel, silver, and gold. The resist is cured using actinic radiation. The portion of the metal not covered with resist is etched away to form a pattern of electrode current tracks.

  The compositions and methods can be used in the manufacture of electronic device components, such as PCBs, and lead frames, optoelectronic devices, photovoltaic devices, and metal finishing of components and precision tools. They have good image sharpness and low fluidity due to their phase change properties.

  The following examples are intended to further illustrate the present invention and are not intended to limit the scope of the invention.

Example 1-7
Inkjet etching resist composition

  All seven formulations are made in the same way. Using conventional laboratory blending equipment, the monomer, acid wax and radical initiator are blended together to form a uniform mixture. Heating is performed at 50 ° C. to 90 ° C. in a conventional convection oven to liquefy any ingredients that are too hard to blend with the other ingredients. After mixing, each component is then cooled to room temperature to form a 100% solids composition. This composition is expected to have an acid number greater than 100 mg KOH / g.

All viscosities are expected to be 15 cp or less using a Brookfield viscometer with a thermosel attachment at temperatures of 60 ° C., 80 ° C. and 100 ° C. Thus, the composition is expected to be suitable for conventional ink jet devices, for example, ink jets using Directmask ^™ DoD300 obtained from Schmid.

Example 8
Etch Resist PCB Application The resist composition from Examples 1-7 was obtained from a piezoelectric drop-on-demand printhead (Spectra ^™ SE-128) onto 7 separate copper clad FR4 / glass-epoxy panels. The ink is selectively ink-jetted with a thickness of 30 μm. The temperature during inkjet is 65 ° C to 95 ° C. The resist composition is selectively applied to each panel, the composition, using FusionD valve operating in 120 W / ^cm, is exposed to UV light at ^{150mJ / cm 2 ~200mJ / cm 2} . All resists are expected to cure.
The hardness of each resist is tested using the ASTM D3363-05 pencil hardness test. The hardness value is expected to be 3H or higher. The hardest value that can be obtained is 5H and the softest is 1H.
Each panel is then immersed in an aqueous etch solution of 4N CuCl ₂ etchant at 50 ° C. for 5 minutes to etch away the portions of copper that are not covered with resist. Copper is etched to a depth of 38 μm. The resist composition is expected to withstand the etching action of the CuCl ₂ etchant. After etching is complete, the panel is removed from the etchant and rinsed with water.
Each panel is then dipped in a bath of 2.5 wt% aqueous sodium hydroxide stripping solution at 40 ° C. to 50 ° C. for 1 minute to strip the resist from the panel. It is expected that substantially all of the resist will be removed from each panel, leaving a copper circuit pattern on the panel. The panel is then further processed to complete the production of the PCB for the electronic device.

Example 9
Etching resist for semiconductor applications Seven doped single crystal silicon semiconductor wafers with pn-junctions are provided. The front or emitter layer of the doped single crystal silicon wafer is textured and n ++ doped. The back side is p ++ doped with aluminum. The region between the n ++ doped emitter layer and the p ++ doped backside is n + doped. The front side of the doped single crystal silicon wafer is coated with a 500 nm thick layer of Si ₃ N ₄ . Si ₃ N ₄ is a dielectric that functions as an antireflection layer.
The anti-reflective layer of each silicon wafer is selectively selected from any of the seven resist compositions of Examples 1-7 at 80 ° C.-100 ° C. by a drop-on-demand ink jet printer to form current tracks. Coated. The resist composition is deposited so that the distance between each current track is 3 mm. The resist is deposited on the dielectric layer with a thickness of 10 μm. The resist is then exposed to UV light at 150-2000 mJ / cm ² by a fusion UV belt system. All resists are expected to cure.
The hardness of each resist is tested using the ASTM D3363-05 pencil hardness test. The hardness value is expected to be 3H or higher. The hardest value that can be obtained is 5H and the softest is 1H.
The Si ₃ N ₄ dielectric layer that is not covered with resist is then etched away to expose regions of the n ++ doped emitter layer. In order to expose the emitter layer, the etching is performed using an aqueous 40% hydrofluoric acid etchant at 25 ° C. for 2-10 minutes to form a current track 20 μm wide and 0.5 μm deep. This acid etchant is not expected to etch away the etching resist. The aluminum back side of the wafer is also protected from the acid etchant during etching by the same resist applied to the front side of the wafer.
The front side of the wafer is sprayed at 40 ° C. to 50 ° C. with an aqueous stripping solution of 2.5% by weight sodium hydroxide to strip off the resist. It is expected that substantially all of the resist will be removed from each wafer so that no residue remains that will aggravate the metal plating. The wafer current track is then plated with electroless nickel to form a 0.1 μm thick nickel seed layer. Nickel is deposited using a Niplate ^™ 600 mid-phosphorous electroless nickel bath (available from Rohm and Haas Electronic Materials, LLC, Marlborough, Mass., USA). The nickel seed layer is then coated with a 10 μm thick silver layer. An Enlight ^™ 600 silver plating bath (available from Rohm and Haas Electronic Materials, LLC) is used to deposit silver by conventional light-induced plating.

Example 10
Plating Resist for PCB Application The resist composition from Examples 1-7 is from a piezoelectric drop-on-demand printhead (Spectra ^™ SE-128) on 7 separate epoxy panels with a thickness of 15-30 μm. Then, ink jet is selectively performed. The epoxy panel has a 1 micron ultra-thin copper seed layer. The temperature during inkjet is 65 ° C to 95 ° C. The resist composition is selectively applied to each panel, the composition, using FusionD valve operating in 120 W / ^cm, is exposed to UV light at ^{150mJ / cm 2 ~200mJ / cm 2} . All resists are expected to cure.
The hardness of each resist is tested using the ASTM D3363-05 pencil hardness test. The hardness value is expected to be 3H or higher. The hardest value that can be obtained is 5H and the softest is 1H.
Each panel with the cured resist is placed in a copper electroplating bath containing 80 g / L copper sulfate pentahydrate, 225 g / L sulfuric acid, 50 ppm chloride ions and 1 g / L polyethylene oxide. Electroplating is performed at 1 amp / dm ² . Copper metal is deposited on the panel in areas not covered with resist. Copper deposition is performed until the copper deposit is 15 μm to 25 μm thick.
Each panel is then dipped in a bath of 2.5 wt% aqueous sodium hydroxide stripping solution at 40 ° C. to 50 ° C. for 1 minute to strip the resist from the panel. It is expected that substantially all of the resist will be removed from each panel, leaving a copper circuit pattern on the panel. The panel is then further processed to complete the production of the PCB for the electronic device.

Example 11
Seven doped single crystal silicon semiconductor wafers with plating resist pn-junctions for solar cell applications are provided. The front or emitter layer of the doped single crystal silicon wafer is textured and n ++ doped. The back side is p ++ doped with aluminum. In addition, the backside also includes a 10 μm thick aluminum layer that is chemically vapor deposited. The region between the n ++ doped emitter layer and the p ++ doped backside is n + doped. The front side of the doped single crystal silicon wafer is coated with a 500 nm thick layer of Si ₃ N ₄ . Si ₃ N ₄ is a dielectric that functions as an antireflection layer.
The aluminum layer of each silicon wafer is one of the seven resist compositions of Examples 1-7 at 80 ° C.-100 ° C. by a drop-on-demand ink jet printer to form current tracks on the back side of the wafer. Is selectively coated. The resist composition is deposited so that the distance between each electrode track is 3 mm. The resist is deposited on the aluminum layer with a thickness of 15-30 μm. The resist is then exposed to UV light at 150-2000 mJ / cm ² by a fusion UV belt system. All resists are expected to cure.
The hardness of each resist is tested using the ASTM D3363-05 pencil hardness test. The hardness value is expected to be 3H or higher. The hardest value that can be obtained is 5H and the softest is 1H.
It is then covered with resist using a conventional etching bath consisting of 5 wt% acetic acid, 80 wt% phosphoric acid, 5 wt% nitric acid, and 10 wt% distilled water to etch the aluminum metal. The areas of the aluminum layer not etched are etched to remove the exposed aluminum. The backside of each wafer is sprayed at 40 ° C. to 50 ° C. with an aqueous stripping solution of 2.5% by weight sodium hydroxide to strip off the resist. A pattern of aluminum current tracks remains on the back surface to function as the anode.

Claims (9)

  A composition comprising one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators.   The composition of claim 1, wherein the acid value of the one or more waxes is at least 100 mg KOH / g.   The composition according to claim 2, wherein the acid value of the one or more waxes is 120 mgKOH / g to 170 mgKOH / g.   The composition of claim 1, wherein the composition further comprises one or more colorants.   The composition of claim 1, wherein the composition does not comprise an acid group-containing acrylate functional monomer. a) providing a composition comprising one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators;
b) selectively depositing the composition on the substrate;
c) applying actinic radiation to the composition to cure the composition;
d) etching portions of the substrate not covered with the cured composition; and e) using a base to remove the cured composition from the substrate to form a patterned article;
A method involving that.   The method of claim 6, wherein the acid value of the one or more waxes is at least 100 mg KOH / g.   7. The method of claim 6, wherein the substrate is selected from printed circuit board components, photovoltaic elements, optoelectronic elements, metal components and lead frames. a) providing a composition comprising one or more acid waxes, one or more acid group-free acrylate functional monomers, and one or more radical initiators;
b) selectively depositing the composition on the substrate;
c) applying actinic radiation to the composition to cure the composition;
d) metal plating on the portion of the substrate not covered with the cured composition; and e) using a base to remove the cured composition to form a patterned article;
A method involving that.